cellularAutomaton.js

function cellularAutomaton(matrix) {
  const tmpMatrix = copyMatrix(matrix);
  tmpMatrix.forEach((row, rowIndex) => {
    row.forEach((pixel, pixelIndex) => {
      tmpMatrix[rowIndex][pixelIndex] = calculatePixelValueByNeighbors(rowIndex, pixelIndex, matrix);
    });
  });

  return tmpMatrix;
}

function calculatePixelValueByNeighbors(rowIndex, pixelIndex, matrix) {
	let sum = 0;
	for (let y = -1; y < 2; y++) {
		for (let x = -1; x < 2; x++) {
			if (!matrix[rowIndex + y] || !matrix[rowIndex + y][pixelIndex + x]) {
				sum -= 1;
			} else {
				sum += 1;
			}
		}
	}
	return sum > 0 ? WHITE : BLACK;
}